pedicle screw insertion
- 2. INTRODUCTION Accepted techniques for pedicle screw insertion •Free hand technique •Funnel technioque •In Out In technique •Minimally Invasive Technique •Gear Shift Technique-lesser chances of medial wall perforation.
- 3. Lumbar vertebra Anatomy Body Pedicles Transeverse processs(l3 has longest) Lamina Articular process Spinous process Maxillary process
- 5. Define entry point Opening of the cortex Probe insertion Tapping Screw insertion
- 6. Entry point The entry point of the pedicle screw is defined as the confluence of any of the four lines: Pars interarticularis Mamillary process Lateral border of the superior articular facet Mid transverse process.
- 7. Opening of Cortex Open the superficial cortex of the entry point with a burr or a rongeur or a nibbler.
- 8. Creating the Pedicle Tract A entry owl is used to navigate down the isthmus of the pedicle into the vertebral body. The appropriate trajectory of the pedicle probe is required in both cranial caudal direction and mediolateral direction.
- 9. Cranio Caudal Angulation The appropriate trajectory of the pedicle probe in the cranial caudal direction occurs by aiming for the contralateral transverse process thereby aiming to be parallel to the superior endplate.
- 10. Medio Lateral Inclination L1 has 5 degree medial convergence in most cases There is 5 degrees of additional convergence below L1 Thus L2 has 10 degrees, L3 has 15 degrees and so on
- 11. we advance it 20 mm with the tip pointing laterally as a safety measure to prevent medial pedicle wall breach. At this point the tip would have traversed the pedicle It is then removed, rotated 180 degrees so that the tip points medially and advanced into the body
- 12. Probing A ball tip probe is used to palpate 5 surfaces (medial, lateral, superior, inferior and floor) to check their integrity.
- 13. We then either undertap by 1mm or don’t tap at all to optimise screw purchase Pedicle path is again palpated with the ball tip probe and length of the tract is marked with a clamp Tapping
- 14. Screw Insertion Pedicle screw is inserted which crosses the pedicle and 80% of the vertebral body
- 15. How to increase pullout strength of pedicle screw Length – 2/3 of the body Larger diameter screw Larger pitch of screw Use of interconnecting/ cross fixation rods
- 16. Patient Profile 25 yr male H/o fall in well Presented with traumatic l1 wedging with paraplegia with bladder bowel involvement with out bedsores
- 17. Pre operative
- 18. Post Operative X rays
- 19. Thank you